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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.] */
#include <openssl/bn.h>
#include <assert.h>
#include <limits.h>
#include "internal.h"
void bn_big_endian_to_words(BN_ULONG *out, size_t out_len, const uint8_t *in,
size_t in_len) {
// The caller should have sized |out| to fit |in| without truncating. This
// condition ensures we do not overflow |out|, so use a runtime check.
BSSL_CHECK(in_len <= out_len * sizeof(BN_ULONG));
// Load whole words.
while (in_len >= sizeof(BN_ULONG)) {
in_len -= sizeof(BN_ULONG);
out[0] = CRYPTO_load_word_be(in + in_len);
out++;
out_len--;
}
// Load the last partial word.
if (in_len != 0) {
BN_ULONG word = 0;
for (size_t i = 0; i < in_len; i++) {
word = (word << 8) | in[i];
}
out[0] = word;
out++;
out_len--;
}
// Fill the remainder with zeros.
OPENSSL_memset(out, 0, out_len * sizeof(BN_ULONG));
}
BIGNUM *BN_bin2bn(const uint8_t *in, size_t len, BIGNUM *ret) {
BIGNUM *bn = NULL;
if (ret == NULL) {
bn = BN_new();
if (bn == NULL) {
return NULL;
}
ret = bn;
}
if (len == 0) {
ret->width = 0;
return ret;
}
size_t num_words = ((len - 1) / BN_BYTES) + 1;
if (!bn_wexpand(ret, num_words)) {
BN_free(bn);
return NULL;
}
// |bn_wexpand| must check bounds on |num_words| to write it into
// |ret->dmax|.
assert(num_words <= INT_MAX);
ret->width = (int)num_words;
ret->neg = 0;
bn_big_endian_to_words(ret->d, ret->width, in, len);
return ret;
}
BIGNUM *BN_lebin2bn(const uint8_t *in, size_t len, BIGNUM *ret) {
BIGNUM *bn = NULL;
if (ret == NULL) {
bn = BN_new();
if (bn == NULL) {
return NULL;
}
ret = bn;
}
if (len == 0) {
ret->width = 0;
ret->neg = 0;
return ret;
}
// Reserve enough space in |ret|.
size_t num_words = ((len - 1) / BN_BYTES) + 1;
if (!bn_wexpand(ret, num_words)) {
BN_free(bn);
return NULL;
}
ret->width = (int)num_words;
// Make sure the top bytes will be zeroed.
ret->d[num_words - 1] = 0;
// We only support little-endian platforms, so we can simply memcpy the
// internal representation.
OPENSSL_memcpy(ret->d, in, len);
return ret;
}
BIGNUM *BN_le2bn(const uint8_t *in, size_t len, BIGNUM *ret) {
return BN_lebin2bn(in, len, ret);
}
// fits_in_bytes returns one if the |num_words| words in |words| can be
// represented in |num_bytes| bytes.
static int fits_in_bytes(const BN_ULONG *words, size_t num_words,
size_t num_bytes) {
const uint8_t *bytes = (const uint8_t *)words;
size_t tot_bytes = num_words * sizeof(BN_ULONG);
uint8_t mask = 0;
for (size_t i = num_bytes; i < tot_bytes; i++) {
mask |= bytes[i];
}
return mask == 0;
}
void bn_assert_fits_in_bytes(const BIGNUM *bn, size_t num) {
const uint8_t *bytes = (const uint8_t *)bn->d;
size_t tot_bytes = bn->width * sizeof(BN_ULONG);
if (tot_bytes > num) {
CONSTTIME_DECLASSIFY(bytes + num, tot_bytes - num);
for (size_t i = num; i < tot_bytes; i++) {
assert(bytes[i] == 0);
}
(void)bytes;
}
}
void bn_words_to_big_endian(uint8_t *out, size_t out_len, const BN_ULONG *in,
size_t in_len) {
// The caller should have selected an output length without truncation.
declassify_assert(fits_in_bytes(in, in_len, out_len));
// We only support little-endian platforms, so the internal representation is
// also little-endian as bytes. We can simply copy it in reverse.
const uint8_t *bytes = (const uint8_t *)in;
size_t num_bytes = in_len * sizeof(BN_ULONG);
if (out_len < num_bytes) {
num_bytes = out_len;
}
for (size_t i = 0; i < num_bytes; i++) {
out[out_len - i - 1] = bytes[i];
}
// Pad out the rest of the buffer with zeroes.
OPENSSL_memset(out, 0, out_len - num_bytes);
}
size_t BN_bn2bin(const BIGNUM *in, uint8_t *out) {
size_t n = BN_num_bytes(in);
bn_words_to_big_endian(out, n, in->d, in->width);
return n;
}
int BN_bn2le_padded(uint8_t *out, size_t len, const BIGNUM *in) {
if (!fits_in_bytes(in->d, in->width, len)) {
return 0;
}
// We only support little-endian platforms, so we can simply memcpy into the
// internal representation.
const uint8_t *bytes = (const uint8_t *)in->d;
size_t num_bytes = in->width * BN_BYTES;
if (len < num_bytes) {
num_bytes = len;
}
OPENSSL_memcpy(out, bytes, num_bytes);
// Pad out the rest of the buffer with zeroes.
OPENSSL_memset(out + num_bytes, 0, len - num_bytes);
return 1;
}
int BN_bn2bin_padded(uint8_t *out, size_t len, const BIGNUM *in) {
if (!fits_in_bytes(in->d, in->width, len)) {
return 0;
}
bn_words_to_big_endian(out, len, in->d, in->width);
return 1;
}
BN_ULONG BN_get_word(const BIGNUM *bn) {
switch (bn_minimal_width(bn)) {
case 0:
return 0;
case 1:
return bn->d[0];
default:
return BN_MASK2;
}
}
int BN_get_u64(const BIGNUM *bn, uint64_t *out) {
switch (bn_minimal_width(bn)) {
case 0:
*out = 0;
return 1;
case 1:
*out = bn->d[0];
return 1;
#if defined(OPENSSL_32_BIT)
case 2:
*out = (uint64_t) bn->d[0] | (((uint64_t) bn->d[1]) << 32);
return 1;
#endif
default:
return 0;
}
}